With the letters "LU" on a nearby hillside, Mitt Romney, U.S. Republican presidential candidate and former Massachusetts governor, speaks at the Liberty University commencement ceremony in Lynchburg, Virginia May 12, 2012. Liberty University, founded by the late television evangelist Jerry Falwell, is a bastion for conservative Christian thought.

Mitt Romney was received with loud applause at Liberty University Saturday morning as he called on graduates to let "the message of Jesus Christ" be their guide and also as he reaffirmed the traditional definition of marriage.

"Marriage is a relationship between one man and one woman," the presumptive Republican presidential nominee asserted, receiving a standing ovation, days after President Barack Obama expressed support for same-sex marriage.

In his commencement address at the Lynchburg, Va., university, Romney – a Mormon – focused much of his speech on faith, family and service.

"Today, thanks to what you have gained here, you leave Liberty with conviction and confidence as your armor. You know what you believe. You know who you are. And you know whom you will serve," he told more than 14,000 graduates, Liberty's largest graduating class. "Moral certainty, clear standards, and a commitment to spiritual ideals will set you apart in a world that searches for meaning.

"That said, your values will not always be the object of public admiration. In fact, the more you live by your beliefs, the more you will endure the censure of the world. Christianity is not the faith of the complacent, the comfortable or of the timid."

Romney acknowledged during his speech at the evangelical Christian university that his faith is different from theirs. But he pointed out the common ground on which they can meet – in service and "shared moral convictions."

The former Massachusetts governor's invitation to deliver the commencement speech was met with protest by some who argued that Mormonism is not part of the Christian faith. Jerry Falwell, Jr., chancellor of Liberty, told The Christian Post earlier, however, that Liberty has a long tradition of inviting leaders from business and politics who are not necessarily evangelicals. And each time they make such an invitation, they deal with the same questions.

Explaining his reason for extending an invitation to Romney this year, Falwell said, "He has reached a pinnacle of success in his business career and I believe our graduates can gain valuable insight into what traits and skills it takes for a person with high moral standards to succeed in today's competitive business environment."

According to Liberty, which was founded in 1971, this year's commencement ceremony saw its largest crowd ever with more than 30,000.

Throughout his address, Romney, who graduated from Brigham Young University in 1971, encouraged graduates to hold firm to their convictions.

"All that you have heard here at Liberty University – about trusting in God and in His purpose for each of us – makes for more than a good sermon. It makes for a good life," he stated.

"What we have, what we wish we had – ambitions fulfilled, ambitions disappointed … investments won, investments lost … elections won, elections lost – these things may occupy our attention, but they do not define us," he added. "Our relationship with our Maker, however, depends on none of this.

"Our worldly successes cannot be guaranteed, but our ability to achieve spiritual success is entirely up to us, thanks to the grace of God. The best advice I know is to give those worldly things your best but never your all, reserving the ultimate hope for the only one who can grant it."

As he sought to connect with evangelicals, he expressed his intent to protect religious liberty and the unborn. Also, in an attempt to woo young evangelical voters who will be facing a weak job market, Romney noted that "job opportunities are scarce in this economy" but he hinted at how they can see a brighter future.

"If we take the right course, we will see a resurgence in the American economy that will surprise the world, and that will open new doors of opportunity for those who are prepared as you are," he said.

He immediately followed with, "Of course, what the next four years might hold for me is yet to be determined. But I will say that things are looking up, and I take your kind hospitality today as a sign of good things to come."

Citing Harvard historian David Landes who sought to understand why some civilizations rise and others falter, he emphasized, "Culture makes all the difference. Not natural resources, not geography, but what people believe and value."

Days before the commencement ceremony, the Public Religion Research Institute released a poll revealing that a majority of white evangelical Christians (67 percent) who believe Romney's Mormon faith is different than their own faith said they would vote for Romney over Obama if the election were held today.